<template>
  <!-- 当为0时，底部不显示 -->
  <div class="todo-footer" v-show="total">
    <label>
      <!-- :check = "isAll"用于初始化复选框
            @change="checkAll"用来更新复选框
       -->
      <!-- <input type="checkbox" :checked="isAll" @change="checkAll" /> -->
      <!-- 简写为 -->
      <input type="checkbox" v-model="isAll" />
    </label>
    <span>
      <span>已完成{{ doneTotal }}</span> / 全部{{ total }}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: 'MyFooter',
  props: ["todos", "checkAllTodo", "clearAllTodo"],
  computed: {
    total () {
      return this.todos.length
    },
    doneTotal () {
      return this.todos.reduce((prev, cur) => {
        return prev + (cur.done ? 1 : 0)
      }, 0)
      // 简写
      // return this.todos.reduce((prev, current) => prev + (current.done ? 1 : 0))
    },
    isAll: {
      get () {
        return this.doneTotal === this.total && this.total > 0
      },
      set (value) {
        this.checkAllTodo(value)
      }
    }
  },
  methods: {
    // 清除所有已完成的todo
    clearAll () {
      this.clearAllTodo()
    }
    // checkAll (e) {
    //   // 获取到当前元素有没有被选
    //   console.log(e.target.checked);
    //   this.checkAllTodo(e.target.checked)
    // }
  }
}
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>